The objective of this project is to characterize the DNA, RNA, and chromosomes of dinoflagellates in order to ascertain their relationship to prokaryotes and eukaryotes. During the coming year we plan to complete the quantitative studies of unique-repeated DNA interspersion on the dinoflagellate Crypthecodinium cohnii. These quantitative studies require that we obtain DNA of a narrow, accurately known size class. We have already successfully developed preparative and analytic agarose gels for this purpose. Using an artifact-free agarose gel system for sizing RNA molecules, developed by our colleagues at Harvard, we plan to measure the size of the three major ribosomal RNAs of C. cohnii to determine if these RNAs are prokaryotic size, eukaryotic size, or in between. We plan also to study the gene arrangement of the ribosomal RNAs of C. cohnii to determine if the three size classes are located on the DNA near each other as in prokaryotes or located on different chromosomes as in eukaryotes. If time permits, we plan to use DNA-RNA hybridization to find the total complexity of RNA in C. cohnii in order to determine why such primitive organisms contain so much unique DNA; that is, is all the unique DNA actually genes. BIBLIOGRAPHIC REFERENCES: Loeblich, A.R. III. 1977. Dinoflagellate genetics and DNA characterization. Stadler Genetics Symposium, Univ. Missouri, Columbia 8: 18 pp., in press. Roberts, T.M., L.C. Klotz and A.R. Loeblich III., 1977. Characterization of a blue-green algal genome. J. Molecular Biol. 109:21 pp., in press.